The need exists for the fabrication of ceramic materials having improved electronic properties which may be adjusted for a particular, intended use. The present invention deals with novel ceramic ferroelectric materials having ideal properties for use, for example, in phased array antenna systems.
Ferroelectric materials which are commonly used in the antenna arts are porous ceramics, whose properties are less than ideal for their intended application. Porous ceramics of the Ba.sub.1-x Sr.sub.x TiO.sub.3 type are commonly employed in ceramic phase shifter antennas. However, these materials display certain deficiencies due to both the processing difficulties and expense, as well as their overall electronic and microwave properties. These deficiencies include electronic inhomogeneity, structural weakness, reproducibility and processing control, and large loss tangents.
Barium Strontium Titanate (BaTiO.sub.3 -SrTiO.sub.3), also referred to herein as BSTO, has been known to be used for its high dielectric constant (approximately ranging from 200 to 6,000) in various antenna applications. This is set forth by Richard W. Babbitt et al. in their publication, "Planar Microwave Electro-Optic Phase Shifters," Microwave Journal, Volume 35(6), (June 1992). This publication concludes that there exists a need for additional research to be conducted in the materials art to yield materials having more desirable electronic properties.
Although the employ of BSTO in phase shifters is known, nowhere in the technical arena of ceramic art has there been any suggestion of modifying BSTO, or combining BSTO with additives, in the manner described herein. Moreover, the specific BSTO combinations, which have enhanced electronic properties, are deemed novel.
The present invention provides for improved materials which exhibit electronic properties which can be adjusted for use, for example, in any discrete element phase shifter design--i.e. planar microstrip, wave guide geometries or parallel plate structure. The invention herein is superior to other currently used ferroelectric materials in the art.